Modeling node mobility for reliable packet delivery in mobile ip networks

In this paper, we analyze node mobility for reliable packet delivery in mobile IP networks. In mobile IP, packets destined to roaming nodes are intercepted by their home agents and delivered via tunneling to their care of addresses (CoA). A mobile node may roam across multiple subnets. At each boundary crossing, a handoff is initiated such that the CoA is updated and a new tunnel is established. We consider both basic mobile IP handoff and smooth handoff. We find that reliable packet delivery in mobile IP networks can be modeled as a renewal process, because the retransmission over a new tunnel after each boundary crossing is independent of the previous history. We then derive the probability distribution of boundary crossings for each successful packet, based on which the packet reliable delivery time can be obtained. Our analytical model is derived based on a general distribution of residence time in a subnet and a general distribution of successful retransmission attempts in each subnet. The results can be readily applied to any distributions for both items. We also provide numerical examples to calculate the probability distribution of boundary crossings, and conduct simulations to validate our analytical results     

IMS应用层连续性研究

应用层移动性对在移动环境下的IP应用很重要,底层的移动性支持保证了切换中数据传输的平滑性,而应用层移动性要保证上层应用在移动中正确收发数据。文中提出了移动扩展SOCKET,即MESOCK(Mobile Extension SOCKET)来实现应用层的移动性。它允许应用数据传送中变换数据传输的源和目的IP地址,使得数据可以直接经路由到达目的地而不是采用隧道的方式。能够很好地配合底层的IP地址切换,即终端地址一旦变化,应用层即启用新的IP地址来收发数据,而不是通过数据隧道发送数据。并在地址切换过程中很好地保持连接的持续性,从而保证服务的连续性和数据传输的完整性。仿真结果证明MESOCK可以很好地实现这一目标。     

Mobile IP中的切换技术

介绍了MobileIP的基本概念和其中的切换问题,分析了影响切换时通信性能的3个因素:移动检测、重新注册以及与上层协议的相互作用,提出了新的切换方案:将链路标识嵌入到FA的代理广播消息中,使得MH可以据此进行快速的移动检测;MH为发送端时,切换后主动发送未应答的TCP包;MH为接收端时,切换后通过主动发送多个TCPSACK包来请求发送端发送已丢失的TCP包。计算机仿真结果表明新的方案具有良好的性能。     

Fast and scalable wireless handoffs in support of mobile Internet audio

Future internetworks will include large numbers of portable devices moving among small wireless cells. We propose a hierarchical mobility management scheme for such networks. Our scheme exploits locality in user mobility to restrict handoff processing to the vicinity of a mobile node. It thus reduces handoff latency and the load on the internetwork. Our design is based on the Internet Protocol (IP) and is compatible with the Mobile IP standard. We also present experimental results for the lowest level of the hierarchy. We implemented our local handoff mechanism on Unix-based portable computers and base stations, and evaluated its performance on a WaveLAN network. These experiments show that our handoffs are fast enough to avoid noticeable disruptions in interactive audio traffic. For example, our handoff protocol completes less than 10 milliseconds after a mobile node initiates it. Our mechanism also recovers from packet losses suffered during the transition from one cell to another. This work helps extend Internet telephony and teleconferencing to mobile devices that communicate over wireless networks. This revised version was published online in June 2006 with corrections to the Cover Date.     

移动因特网半软切换的仿真研究

MobileIP协议中原有的硬切换算法产生的分组丢失和切换时延大大降低了用户的通信质量，半软切换算法是硬切换的改进算法，本文通过仿真比较了Mobile IP协议中硬切换和半软切换对TCP和UDP流量的影响，并进一步研究了影响半软换性能的因素。     

一种基于无线局域网的移动检测优化方案

无线局域网采用移动IP实现移动性管理.移动IP切换存在切换时延大,数据包易丢失的问题.切换时延由移动检测时延和注册时延组成,而移动检测时延在其中占主要部分.文章提出了一种移动检测优化方案,采用了自适应绑定的算法,同时充分考虑了域内小范围高频度切换的情况,使移动节点在无线局域网环境中进行快速有效的切换.     

A Comprehensive Analysis of Mobility Management in MPLS-Based Wireless Access Networks

Efficient mobility management is one of the major challenges for next-generation mobile systems. Indeed, a mobile node (MN) within an access network may cause excessive signaling traffic and service disruption due to frequent handoffs. The two latter effects need to be minimized to support quality-of-service (QoS) requirements of emerging multimedia applications. In this perspective, we propose in this paper a new mobility management scheme designed to track host mobility efficiently so as to minimize both handoff latency and signaling cost. Building on and enhancing Mobile IP and taking advantage of MPLS traffic engineering capability, three mechanisms (FH-, FC- and MFC-Micro Mobile MPLS) are introduced. In order to assess the efficiency of our proposals, all protocols are compared. To achieve this, we develop analytical models to evaluate the signaling cost and link usage for both two-dimensional and one-dimensional mobility models. Additional mathematical models are also provided to derive handoff latency and packet loss rate. Numerical and simulation results show that the proposed mechanisms can significantly reduce the registration updates cost and provide low handoff latency and packet loss rate under various scenarios.      

The effect of Mobile IP handoffs on the performance of TCP

Mobile IP is a standard for handling routing for hosts that have moved from their home network. This paper studies the costs of the Mobile IP handoff that occurs when a mobile host moves between networks. Experiments were carried out with Mobile IP and TCP over varying network conditions to observe the effect of handoffs on the transmission. This paper shows that although Mobile IP may be appropriate for current applications, its long handoff periods make it unsuitable for the future.     

Micro mobility in the IP networks

Wireless access to Internet services will become typical, rather than the exception as it is today. Such a vision presents great demands on mobile networks. Mobile IP represents a simple and scalable global mobility solution but lacks the support for fast handoff control and paging found in cellular telephony networks. In contrast, second- and third-generation cellular systems offer seamless mobility support but are built on complex and costly connection-oriented networking infrastructure that lacks the inherent flexibility, robustness, and scalability found in IP networks. This paper presents an overview and performance comparison of two of the main micro-mobility protocols, namely Cellular IP and Hierarchical Mobile IP with regards to the handoff process for UDP applications. The differences in the handoff quality of the two protocols are small and can be traced to design choices within the typical model. There are however significant differences regarding the processing requirement, routing efficiency and parameters relating to implementation and deployment.     

Topology-aided cross-layer fast handoff designs for IEEE 802.11/mobile IP environments

This study first reviews state-of-the-art fast handoff techniques for IEEE 802.11 or Mobile IP networks. Based on that review, topology-aided cross-layer fast handoff designs are proposed for Mobile IP over IEEE 802.1.1 networks. Time-sensitive applications, such as voice over IP (VoIP), cannot tolerate the long layer-2 plus layer-3 handoff delays that arise in IEEE 802.11/Mobile IP environments. Cross-layer designs are increasingly adopted to shorten the handoff latency time. Handoff-related layer-2 triggers may reduce the delay between layer-2 handoff completion and the associated layer-3 handoff activation. Cross-layer topology information, such as the association between 802.11 access points and Mobile IP mobility agents, together with layer-2 triggers, can be utilized by a mobile node to start layer-3 handoff-related activities, such as agent discovery, address configuration, and registration, in parallel with or prior to those of layer-2 handoff. Experimental results indicate that the whole handoff. delay can meet the delay requirement of VoIP applications when layer-3 handoff activities occur prior to layer-2 handoffs.     

移动互联网TCP性能精细化评估方法研究

移动网络中数据传输流量与速率与日俱增,如何评估数据业务传输过程中TCP的性能成为运营商研究的重点。主要提出了一种TCP性能评估的方法,该方法除了对于TCP连接过程中的连接时延,数据包重传问题进行了统计以外,还对TCP的实时统计速率进行了相应的算法改进,即符合移动互联网用户数据流量使用规律的统计方法,其最大的特点在于消除静默时间内均化速率造成的不准确性。此外,在移动网络实验环境下对本评估方法进行测试,对比了传统的整体化性能评估方法,精细化的评估方法在牺牲一定内存消耗的条件下,提升了TCP性能统计的精确性。     

A Comparison of Performance between Macro-mobility Protocol and Micro-mobility Protocol

1　IntroductionAlthoughthemobileIP protocol[1～3] workswellinthemacromobilitysituation ,someproblemsoccurinthemicromobilitysituation .Therearetwomainconcerns.First,theregistrationdelaycon tributestothehandoffdelay .Thedelayissignifi cantwhenanMNisfarawayfromhomeandcausessignificantpacketdropanddrasticreductionincom municationthroughput.Second ,frequentlocationupdatesincurextensiveoverheadforlocationcachemanagementinrouteoptimizationthatrequiresac curatelocationinformationinordertotunnelIPda…     

Intelligent Handoff for Mobile Wireless Internet

This paper presents an intelligent mobility management scheme for Mobile Wireless InterNet – MWIN. MWIN is a wireless service networks wherein its core network consisting of Internet routers and its access network can be built from any Internet-capable radio network. Two major standards are currently available for MWIN, i.e., the mobile IP and wireless LAN. Mobile IP solves address mobility problem with the Internet protocol while wireless LAN provides a wireless Internet access in the local area. However, both schemes solve problems independently at different layers, thereby some additional problems occur, e.g., delayed handoff, packet loss, and inefficient routing. This paper identifies these new problems and performs analyses and some real measurements on the handoff within MWIN. Then, a new handoff architecture that extends the features of both mobile IP and wireless LAN handoff mechanism was proposed. This new architecture consists of mobile IP extensions and a modified wireless LAN handoff algorithm. The effect of this enhancement provides a linkage between different layers for preventing packet loss and reducing handoff latency. Finally, some optimization issues regarding network planning and routing are addressed.     

A mobility-based load control scheme in Hierarchical Mobile IPv6 networks

By introducing a mobility anchor point (MAP), Hierarchical Mobile IPv6 (HMIPv6) reduces the signaling overhead and handoff latency associated with Mobile IPv6. In this paper, we propose a mobility-based load control (MLC) scheme, which mitigates the burden of the MAP in fully distributed and adaptive manners. The MLC scheme combines two algorithms: a threshold-based admission control algorithm and a session-to-mobility ratio (SMR)-based replacement algorithm. The threshold-based admission control algorithm gives higher priority to ongoing mobile nodes (MNs) than new MNs, by blocking new MNs when the number of MNs being serviced by the MAP is greater than a predetermined threshold. On the other hand, the SMR-based replacement algorithm achieves efficient MAP load distribution by considering MNs’ traffic and mobility patterns. We analyze the MLC scheme using the continuous time Markov chain in terms of the new MN blocking probability, ongoing MN dropping probability, and binding update cost. Also, the MAP processing latency is evaluated based on the M/G/1 queueing model. Analytical and simulation results demonstrate that the MLC scheme outperforms other schemes and thus it is a viable solution for scalable HMIPv6 networks.     

Integrated Mobility Management Methods for Mobile IP and SIP in IP based Wireless Data Networks

With developments in voice over IP (VoIP), IP-based wireless data networks and their application services have received increased attention. While multimedia applications of mobile nodes are served by Session Initiation Protocol (SIP) as a signaling protocol, the mobility of mobile nodes may be supported via Mobile IP protocol. For a mobile node that uses both Mobile IP and SIP, there is a severe redundant registration overhead because the mobile node has to make location registration separately to a home agent for Mobile IP and to a home registrar for SIP, respectively. Therefore, we propose two new schemes that integrate mobility management functionality in Mobile IP and SIP. We show performance comparisons among the previous method, which makes separate registration for Mobile IP and SIP without integration, and our two integrated methods. Numerical results show that the proposed methods efficiently reduce the amount of signaling messages and delay time related to the idle handoff and the active handoff.     

Low-latency mobile IP handoff for infrastructure-mode wireless LANs

The increasing popularity of IEEE 802.11-based wireless local area networks (LANs) lends them credibility as a viable alternative to third-generation (3G) wireless technologies. Even though wireless LANs support much higher channel bandwidth than 3G networks, their network-layer handoff latency is still too high to be usable for interactive multimedia applications such as voice over IP or video streaming. Specifically, the peculiarities of commercially available IEEE 802.11b wireless LAN hardware prevent existing mobile Internet protocol (IP) implementations from achieving subsecond Mobile IP handoff latency when the wireless LANs are operating in the infrastructure mode, which is also the prevailing operating mode used in most deployed IEEE 802.11b LANs. In this paper, we propose a low-latency mobile IP handoff scheme that can reduce the handoff latency of infrastructure-mode wireless LANs to less than 100 ms, the fastest known handoff performance for such networks. The proposed scheme overcomes the inability of mobility software to sense the signal strengths of multiple-access points when operating in an infrastructure-mode wireless LAN. It expedites link-layer handoff detection and speeds up network-layer handoff by replaying cached foreign agent advertisements. The proposed scheme strictly adheres to the mobile IP standard specification, and does not require any modifications to existing mobile IP implementations. That is, the proposed mechanism is completely transparent to the existing mobile IP software installed on mobile nodes and wired nodes. As a demonstration of this technology, we show how this low-latency handoff scheme together with a wireless LAN bandwidth guarantee mechanism supports undisrupted playback of remote video streams on mobile stations that are traveling across wireless LAN segments.     

An Empirical Analysis of Handoff Performance for SIP,Mobile IP,and SCTP Protocols

Over the last decade, we have witnessed a growing interest in the design and deployment of various network architectures and protocols aimed at supporting mobile users as they move across different types of networks. One of the goals of these emerging network solutions is to provide uninterrupted, seamless connectivity to mobile users giving them the ability to access information anywhere, anytime. Handoff management, an important component of mobility management, is crucial in enabling such seamless mobility across heterogeneous network infrastructures. In this work, we investigate the handoff performance of three of the most widely used mobility protocols namely, Mobile IP, Session Initiation Protocol (SIP), and Stream Control Transmission Protocol (SCTP). Our empirical handoff tests were executed on an actual heterogeneous network testbed consisting of wired, wireless local area, and cellular networks using performance metrics such as handoff delay and handoff signaling time. Our empirical results reveal that Mobile IP yields the highest handoff delay among the three mobility protocols. In addition, we also found that SIP and SCTP yield 33 and 55% lower handoff delays respectively compared to Mobile IP.     

Building Secure Tunnel from PPP Wireless Network

The rapid development of mobile businesses raises the need for exchanging information between mobile computing devices via Internet. If a secure connection is necessary then a virtual private network (VPN) is essential. Currently, VPN protocols set up secure connections between two nodes with fixed IP addresses. However, if several people work in a moving vehicle with their mobiles or computers, the secure connection will be lost due to the IP change and a new connection has to be built from scratch. The current solution to this problem is to run tunnels over Mobile IP (MIP). However, that is inefficient due to double tunneling. In this paper, the authors add a novel form of mobility support to secure L2TP/IPsec tunnels which will be shared by everyone in the vehicle using a Point-to-Point Protocol (PPP) wireless network. The mobility support properly handles the IP change (users may even change to a different kind of network such as from Universal Mobile Telecommunications System (UMTS) to Worldwide Interoperability for Microwave Access (WiMAX) without using an MIP, and without incurring tunnel-re-establishment at handoff. The novel solution achieves better security than current mobility solutions for VPN, and supports fast handoff in IPv4 networks.     

基于IPv6的快速切换改进方案

在移动IP网络中,当前的移动性管理方案由于其基本协议的切换时延较大、丢包率较高而不能适应实时业务和移动通信的要求,所以需要改善移动性管理策略的切换性能,尽量实现无缝切换和零丢包率。提出了一种基于移动IPv6的快速切换的改进方案,采用一种新的地址分配方式使得移动节点能够在移动至新的网络后迅速获取新的转交地址,有效地减少了切换所产生的时延和丢包率,具有较好的切换性能。     

基于可靠UDP的卫星IP网关设计

TCP是面向连接的可靠点到点协议,但是由于卫星网络中典型的长延时、高误码率以及非对称带宽的特点,导致TCP通过宽带卫星网络时,信道利用率非常低。可靠UDP协议基于标准UDP协议并在应用中增加窗口、应答和重传算法来实现。网关采用该协议将TCP连接分段,在应用中明显地改善了TCP在宽带卫星信道上传输的性能,增加TCP的信道利用率。